Audi S3 vs Ford Mustang: Specs Compared

Running cost over five years: at the EPA's 15,000-mile-a-year assumption the Ford Mustang burns about $2,350 of fuel annually against $2,800 for the Audi S3. That $450 yearly gap compounds to roughly $2,250 over five years and $3,600 over eight — often more than the price difference between two trims of the same vehicle, and the single largest running-cost line item separating these two.

City versus highway split: the Audi S3 is the stronger commuter at 23 mpg city, while the Ford Mustang pulls ahead on the interstate at 33 mpg highway. If most of your driving is stop-and-go traffic the city figure is the one to weigh; for long-distance highway mileage the reverse is true, and the two vehicles effectively swap places depending on how you drive.

Powertrain choice: the Audi S3 is recorded with 3 distinct engine configurations (SIDI, SIDI; Mild Hybrid, SIDI;), the Ford Mustang with 4 (5.2, 5.0, SIDI & PFI). Across 11 recorded Audi S3 configurations and 133 for the Ford Mustang, the wider the engine spread the more the real-world fuel efficiency depends on which version you actually buy, so check the specific model year and drivetrain rather than the headline number.

Drivetrain and class: the Audi S3 is offered with All-Wheel Drive, the Ford Mustang with Rear-Wheel Drive. All-wheel drive typically costs one to two mpg combined against the same vehicle in front- or rear-wheel drive, which is worth remembering when the gap between these two is small. The EPA classes them as Subcompact Cars and Subcompact Cars respectively — the class drives the interior volume, cargo space and passenger space each one is measured against.

Tailpipe emissions: at their cleanest configurations the Audi S3 emits 331 g/mile of CO2 versus 341 g/mile for the Ford Mustang. Emissions track fuel consumption almost exactly, so the cleaner vehicle here is also the cheaper one to fuel.